I'm with Kazza. The turn signal is meant for everyone EXCEPT the person using the signal. People get into the habit of using their signal just before they turn because they forget WHY a signal is used. They are just going through the muscle memory motions of flipping the signal, then turning. It sounds a little corny, but driving a car, riding a bike IS operating heavy equipment. This needs to be first and foremost in an operators mind, but who really thinks like that. Most people go into la la land.
Another point is that the REAL hazard wasn't either the rider or the cager who almost hit him, it was the guy out in front, in the left lane, forming a parade behind him. The right lane is for cruising, the left lane for passing. If everyone was operating their machines as a primary task, with safety/strategy in mind, it would be a hell of a lot safer out there.
BTW, if I have to pass on the right, I do it very quickly with my thumb ready to honk.
Glad you're not toast fazer.rider. Something like that happens every 20 minutes on some days of riding...